Muscular Christianity is a philosophical movement that originated in England in the mid-19th century, characterized by a belief in patriotic duty, discipline, self-sacrifice, masculinity, and the moral and physical beauty of athleticism.

The movement came into vogue during the Victorian era as a method of building character in pupils at English public schools. It is most often associated with English author Thomas Hughes and his 1857 novel Tom Brown's School Days, as well as writers Charles Kingsley and Ralph Connor. American President Theodore Roosevelt was raised in a household that practised Muscular Christianity and was a prominent adherent to the movement. Roosevelt, Kingsley, and Hughes promoted physical strength and health as well as an active pursuit of Christian ideals in personal life and politics. Muscular Christianity has continued through organizations that combine physical and Christian spiritual development. It is influential within both Catholicism and Protestantism.